Packaging bag and drying agent with moisture absorpotion indicator function

ABSTRACT

A packaging bag and a drying agent with a moisture absorption indicator function are provided without using a heavy metal harmful to the human body. The packaging bag includes a first packaging material ( 10 ) and a second packaging material ( 20 ). The first packaging material ( 10 ) is provided on an outermost side thereof with a transparent barrier film ( 12 ) having a barrier property against water vapor. The second packaging material ( 20 ) has a light-reflective or light-absorbing film ( 24 ) and a pattern printed layer ( 23 ) overlaid on a bag interior side thereof, the pattern printed layer ( 23 ) having a printed moisture-absorbing indicator pattern ( 30 ). A desiccant-containing resin film ( 11, 21 ) which becomes transparent due to moisture absorption is overlaid on a bag interior side of at least one of the first packaging material ( 10 ) and the second packaging material ( 20 ). The drying agent with a moisture absorption indicator function includes an indicator film layer ( 70 ) having a barrier film ( 75 ), a pattern printed layer ( 73 ) for a moisture absorption indicator, and a moisture-absorbing film ( 71 ) containing zeolite, the pattern printed layer ( 73 ) and moisture-absorbing film ( 71 ) being laminated in this order on the barrier film ( 75 ). The drying agent further includes a main desiccant layer ( 61 ) and a moisture permeable film ( 64 ) that are overlaid on the moisture-absorbing film ( 71 ).

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 11/815,545filed on Aug. 3, 2007 which is a §371 application of PCT/JP2006/301858filed on Feb. 3, 2006, which claims priority from Japanese ApplicationNo. 2005-30999 filed on Feb. 7, 2005 and Japanese Application No.2005-110522 filed on Apr. 7, 2005.

TECHNICAL FIELD

The present invention relates to a packaging bag with a moistureabsorption indicator function and to a drying agent with a moistureabsorption indicator function, and, more particularly, to a packagingbag that hermetically stores various kinds of articles to be protectedfrom moisture, such as a food, electronic component, medicine, ordocument, and that allows visual recognition of a moisture absorbingcondition in the packaging bag and a check on the moisture-proofcapability of the packaging bag itself, and to a sheet-like, plate-like,or bag-like drying agent that contains a main desiccant in the form of asheet, film, or desiccant molded body and that has an indicator functionfor indicating the moisture absorbing condition of such a desiccant.

BACKGROUND ART

Generally, a desiccant made of silica gel, calcium chloride, etc., ispacked in a small bag and is enclosed in a package for use with a dryproduct. This case, however, has inferior workability in packaging.Besides, the silica gel is a white substance, and, therefore, a moistureabsorbing condition in the package cannot be checked from the outside.

To deal with the above problem, a desiccant allowing a check on amoisture absorbing condition, that is, a desiccant with a moistureabsorption indicator function, is provided. Such a desiccant is made bymixing silica gel with cobalt chloride, and it thus is blue in a drycondition while it turns pink upon absorbing moisture in the air.

An example of a drying agent with a moisture absorption indicatorfunction is, for example, shown in FIG. 10, which is constructed as abag-like dehumidifying agent with a humidity indicator. Thisdehumidifying agent is made by storing a moisture absorbent sheet 1 in abag 4 made of a nonwoven fabric, and a moisture-absorbing humidityindicator 2 covered with a barrier film 3 is pasted on the moistureabsorbent sheet 1. The moisture-absorbing humidity indicator 2 containscobalt chloride, and the barrier film 3 has micropores. When themoisture absorbent sheet 1 absorbs moisture, the moisture-absorbinghumidity indicator 2 absorbs moisture through the micropores of thebarrier film 3, thus changing the color of the indicator 2 from blue topink. When the moisture absorbent sheet 1 dries to be regenerated, themoisture-absorbing humidity indicator 2 then changes its color from pinkto blue. Through this color change, the moisture absorption condition ofthe moisture absorbent sheet 1 can be visually recognized (e.g., seepatent document 1).

The conventional example of patent document 1, however, uses cobaltchloride as a moisture absorption indicator substance. When the dryingagent with a moisture absorption indicator using such a heavy metal ascobalt is disposed of as trash and is incinerated, the heavy metal isfinally discharged into the living environment. This is a situation thatpeople hope to avoid as much as possible to protect the environment. Adrying agent having a moisture absorption indicator function but withoutcobalt, therefore, has been developed.

An example of a package having a moisture absorption function is shownin FIG. 11, which is constructed as a cylindrical moisture-absorbingcontainer. This moisture-absorbing container is made by separatelyinjection molding a screw hollow container (outermost layer) 6 and aninner container (innermost layer) 7 and joining both containers togetherinto an integral form. A cap 8 is screwed and tightened on the hollowcontainer 6 to form a storage container. The inner container 7 is moldedout of a resin composition having an indicator function for indicatingmoisture absorptiveness. This resin composition contains a syntheticzeolite 7 a mixed therein, causing the inner container 7 to change itscolor to clear yellow after moisture absorption, which allows an extentof moisture absorption to be checked (e.g., see patent document 2).

-   Patent document 1: Japanese Utility Model Application Laid-Open    Publication No. 64-28934 (entire description, FIG. 1)-   Patent document 2: Japanese Patent Application Laid-Open Publication    No. 2004-331855 (entire description, FIG. 1)

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

The conventional moisture-absorbing container disclosed in patentdocument 2 is a package with an indicator function, which package isprovided in such a form that the storage container consists of theintegrally formed screw hollow container and inner container, and themouth of the storage container is closed with a cap. The inner containerin the storage container is made of a resin composition having anindicator function through means of a color change due to moistureabsorption. This package does not allow effective visual recognition ofa moisture absorbing condition from the outside.

The present invention has been made in view of the above problem.Accordingly, an object of the present invention is to provide apackaging bag with a moisture absorption indicator function, whichpackaging bag has the moisture absorption indicator function, does notcontains a heavy metal harmful to the human body, and enables visualrecognition of such an indicator pattern as characters, numerals, anddesigns from the outside of the packaging bag by making use of aphenomenon that the transparency of a resin film mixed with a desiccantincreases as the resin film absorbs moisture.

Another object of the present invention is to provide a drying agentwith a moisture absorption indicator function, which drying agentincludes a main desiccant layer, has the moisture absorption indicatorfunction, does not contain a heavy metal harmful to the human body, andenables visual recognition of such an indicator pattern as characters,numerals, and designs from the outside by making use of a phenomenonthat the transparency of a resin film mixed with a desiccant increasesas the resin film absorbs moisture.

Means for Solving Problem

The present invention solves the above problem, and provides a novelpackaging bag with a moisture absorption indicator function and a noveldrying agent with a moisture absorption indicator function.

The packaging bag with a moisture absorption indicator functionaccording to the present invention is characterized in that: thepackaging bag comprises a first packaging material and a secondpackaging material joined together while an article storage space beingformed therebetween; at least the first packaging material out of thefirst and second packaging materials includes a transparent barrier filmdisposed on an outermost side thereof, the transparent barrier filmhaving a barrier property against water vapor; the second packagingmaterial includes a light-reflective or light-absorbing film and apattern printed layer disposed on a bag interior side of thelight-reflective or light-absorbing film, the pattern printed layerincluding a moisture absorption indicator pattern; and at least one ofthe first and second packaging materials includes a desiccant-containingresin film that becomes transparent due to moisture absorption, thedesiccant-containing resin film being overlaid on a part or the whole ofthe bag interior side of said at least one of the first and secondpackaging materials. The second packaging material may further include abarrier film on an outermost side thereof, the barrier film having abarrier property against water vapor. The packaging bag is made byhermetically joining together the four sides of the first and secondpackaging materials by heat sealing, etc., and protects a stored articlefrom moisture. The packaging bag includes such a packaging bag that ismade by heat sealing only three sides of the first and second packagingmaterials. This packaging bag is used by storing an article in the bagand hermetically joining the remaining one side by heat sealing, etc.

According to a preferred embodiment of the present invention, thedesiccant-containing resin film comprises a laminate formed of adesiccant-containing resin layer and a thermoplastic resin layer. Thethermoplastic resin layer, for example, should preferably be made ofpolyolefin.

According to a preferred embodiment of the present invention, thetransparent barrier film comprises a base film that is provided thereonwith a silica- or alumina-evaporated film, a multilayer-evaporated filmof silica and alumina, a silicon nitride-evaporated film, a coatinglayer of a barrier paint, or a layer made by coating an evaporated filmwith a barrier paint; and the transparent barrier film has a water vaportransmission rate of 0.001 to 100 g/m²/day. The first packaging materialand the second packaging material should preferably be substantiallyequal in barrier capability.

According to a preferred embodiment of the present invention, thelight-reflective film is a film having a metallic luster that comprisesan aluminum laminate film, an aluminum-evaporated film, aninorganic-evaporated film, or an inorganic oxide-evaporated film; andthe light-reflective film has a water vapor transmission rate of 0.001to 100 g/m²/day. The above inorganic material or inorganic oxideselected is one that does not put a burden on the environment.

According to a preferred embodiment of the present invention, thelight-absorbing film comprises a film coated with or containing alight-absorbing material, or a film laminate having a film coated withor laminated with a light-absorbing material; and the light-absorbingfilm has a water vapor transmission rate of 0.001 to 100 g/m²/day.

According to a preferred embodiment of the present invention, thepattern printed layer comprises a polyolefin film that is provided onthe desiccant-containing resin film or on the light-reflective orlight-absorbing film; the moisture absorption indicator pattern is apattern including a character, numeral, design or a mixture thereofappropriately combined, which is printed on at least one surface of thepolyolefin film; and the desiccant-containing resin film becomestransparent as a desiccant contained in the desiccant-containing resinfilm approaches saturation in moisture absorption, to thereby allowvisual recognition of the moisture absorption indicator pattern from theinside or outside of the packaging bag. Alternatively, the patternprinted layer is provided on the desiccant-containing resin film or onthe light-reflective or light-absorbing film; the moisture absorptionindicator pattern is a pattern including a character, numeral, design ora mixture thereof appropriately combined, which is printed on at leastone surface of the desiccant-containing resin film or of thelight-reflective or light-absorbing film. The moisture absorptionindicator pattern indicates the limit of preservation of an articleagainst moisture. The moisture absorption indicator pattern, forexample, may be characters reading “reaching the preservation limit”, acombination of such characters with designs, or a combination ofcharacters, numerals, etc., having different print densities that can bevisually recognized in the order of a degree of density according to themoisture absorption condition of the desiccant-containing resin film toallow a check on the preservation limit step by step. The polyolefinfilm printed with the moisture absorption indicator pattern may beprovided with a printed layer providing a background color that isformed on the outer surface of the polyolefin film, which outer surfaceis opposite to the surface bearing the moisture absorption indicatorpattern.

According to a preferred embodiment of the present invention, thedesiccant-containing resin film contains at least one desiccant selectedform zeolite, silica gel, and alumina.

According to a preferred embodiment of the present invention, the firstpackaging material is located on a front side of an article stored inthe packaging bag, and the second packaging material is located on aback side of the article.

According to a preferred embodiment of the present invention, thelight-absorbing film is a film printed with black ink, or is a film madeof a thermoplastic resin having carbon black mixed therein.

According to a preferred embodiment of the present invention, thedesiccant-containing resin film is mixed or coated with alight-scattering material, or the transparent barrier film is coatedwith a light-scattering material.

The packaging bag according to the present invention is provided in theform of a three-sided sealed bag, a four-sided sealed bag, a gadget bag,a standing pouch, etc., that is formed of the first packaging materialand the second packaging material and that has the moisture absorptionindicator function. The packaging bag may be provided in such a formthat article storage portions are formed on both sides of the secondpackaging material or at two locations thereon, or that the articlestorage portion of the second packaging material is formed into a boxshape or cylindrical shape.

The drying agent with a moisture absorption indicator function accordingto the present invention is characterized in that the drying agentcomprises: an indicator film layer including a barrier film, a patternprinted layer having a moisture absorption indicator pattern printedthereon, and a moisture-absorbing film becoming transparent due tomoisture absorption, the pattern printed layer and moisture-absorbingfilm being laminated in this order on the barrier film; a main desiccantlayer; and a moisture permeable film, the main desiccant layer and themoisture permeable film being provided on the moisture-absorbing film ofthe indicator film layer. The barrier film may be made of an aluminumlaminate film, aluminum-evaporated film, inorganic-evaporated film, orinorganic oxide-evaporated film. The pattern printed layer is printedwith the moisture absorption indicator pattern of characters, numerals,designs, or a mixture thereof appropriately combined. The main desiccantlayer is made by mixing a thermoplastic resin with a desiccant ofsilicon dioxide (silica gel), calcium oxide, calcium chloride, sulfatecompound, barium oxide, activated carbon, clay compound, etc. The maindesiccant layer may be transparent when not reaching saturation inmoisture absorptiveness, but does not always need to be transparent. Themain desiccant layer is acceptable if it becomes transparent at thepoint that the moisture absorptiveness of the main desiccant layer hasreached saturation.

According to a preferred embodiment of the present invention, a moisturepermeability control film is overlaid on the moisture-absorbing film,the moisture permeability control film controlling the time that elapsesbefore the moisture absorptiveness of the moisture-absorbing filmreaches saturation. The moisture permeability control film shouldpreferably be made of a thermoplastic resin such as polyethyleneterephthalate (PET), polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), nylon (Ny), ethylene vinyl acetate (EVA), polystyrene(PS), ethylene vinyl alcohol copolymer (EVOH), or polyvinylidenechloride (PVDC), or cellophane. The moisture permeability control filmcontrols the moisture absorbing rate of the moisture-absorbing film toprevent such a situation that the moisture absorptiveness of themoisture-absorbing film reaches saturation before the moistureabsorptiveness of the main desiccant layer reaches saturation to allowthe visual recognition of the moisture absorption indicator from theoutside at that point. A moisture absorptiveness retaining time of themoisture-absorbing film is determined according to the main desiccantlayer's moisture absorption capability, such as a moistureabsorptiveness retaining time or the like.

According to a preferred embodiment of the present invention, a space isformed between the main desiccant layer and the moisture-absorbing filmor between the main desiccant layer and the moisture permeabilitycontrol film to provide a bag-like portion.

According to a preferred embodiment of the present invention, the maindesiccant layer comprises a transparent desiccant film or a transparentdesiccant molded body.

According to a preferred embodiment of the present invention, the maindesiccant layer comprises a granular or tabular desiccant or adeliquescent desiccant, and the moisture permeable film and themoisture-absorbing film or the moisture permeable film and the moisturepermeability control film are sealed together at peripheries thereof toform a bag-like portion to enclose therewithin the granular or tabulardesiccant or the deliquescent desiccant. The granular desiccant isprovided as silica gel, etc., the tabular desiccant may be provided as atransparent resin containing silica gel, etc., and the deliquescentdesiccant is provided as calcium chloride, magnesium chloride, potassiumoxide, sodium oxide, alunite, magnesium sulfate, phosphorus oxide, etc.The desiccant stored in the bag-like portion should preferably betransparent or become transparent when the moisture absorptiveness ofthe desiccant reaches saturation, but a nontransparent desiccant is alsoacceptable if the nontransparent desiccant is arranged in such a waythat the indicator pattern at the back of the desiccant can be visuallyrecognized through gaps between the grains of the desiccant.

According to a preferred embodiment of the present invention, themoisture-absorbing film comprises a laminate formed of adesiccant-containing resin layer and a thermoplastic resin.

According to a preferred embodiment of the present invention, themoisture-absorbing film contains at least one desiccant selected fromzeolite, silica gel, and alumina.

According to a preferred embodiment of the present invention, themoisture permeability control film is a transparent film, and has awater vapor transmission rate of 0.01 to 5,000 g/m²/day.

EFFECT OF THE INVENTION

A packaging bag with a moisture absorption indicator function accordingto the present invention includes a first packaging material and asecond packaging material, the first and second packaging materialsbeing joined together while an article storage space being formedtherebetween. At least the first packaging material out of the first andsecond packaging materials includes a transparent barrier film disposedon the outermost side thereof, the transparent barrier film having abarrier property against water vapor. The second packaging materialincludes a light-reflective or light-absorbing film and a patternprinted layer disposed on the bag interior side of the light-reflectiveor light-absorbing film, the pattern printed layer including amoisture-absorbing indicator pattern. At least one of the first andsecond packaging materials includes a desiccant-containing resin filmthat becomes transparent due to moisture absorption, thedesiccant-containing resin film being overlaid on a part or the whole ofthe bag interior side of the one of the first and second packagingmaterials. The desiccant-containing resin film increases itstransparency with increasing moisture absorption. When thedesiccant-containing resin film is overlaid on the bag interior side ofthe first packaging material, therefore, the desiccant-containing resinfilm gradually turns transparent, which allows a check on a storedarticle and visual recognition of the moisture absorption indicatorpattern of the pattern printed layer having an indicator function, thusleading to a confirmation that the moisture absorbing capability of thepackaging bag has reached its limit. When the desiccant-containing resinfilm is overlaid on the bag interior side of the second packagingmaterial, the stored article can be checked in advance, and thedesiccant-containing resin film gradually turns transparent due tomoisture absorption, which allows visual recognition of themoisture-absorbing indicator pattern of the pattern printed layer, thusleading to a confirmation that the moisture absorbing capability of thepackaging bag has reached its limit. When the desiccant-containing resinfilm is overlaid on both first and second packaging materials, thestored article cannot be visually recognized from the outside. When themoisture absorptiveness of the desiccant-containing resin films on bothpackaging materials reaches saturation, however, the moisture absorptionindicator pattern of the pattern printed layer becomes visible, at whichpoint the stored article can be protected from moisture. Overlaying thedesiccant-containing resin film on both first and second packagingmaterials offers an advantage of being able to maintain the moistureabsorption capability in the packaging bag for a long time. In addition,if a pinhole is present on the packaging bag, the desiccant-containingresin film overlaid on the first packaging material and/or the secondpackaging material becomes transparent to cause the moisture absorptionindicator pattern to appear. This facilitates determination on thequality of the packaging bag, and is very effective in managing thecontents of the packaging bag.

When the desiccant-containing resin film comprises a laminate formed ofa desiccant-containing resin layer and a thermoplastic resin layer,desired moisture absorption capability is maintained and the mechanicalstrength of the desiccant-containing resin film is sustained as welleven when the desiccant-containing resin film is overlaid on the firstpackaging material. This makes the desiccant-containing resin filmapplicable to a variety of uses.

When the transparent barrier film comprises a film that is providedthereon with a silica- or alumina-evaporated film, amultilayer-evaporated film of silica and alumina, a siliconnitride-evaporated film, a coating layer of a barrier paint, or a layermade by coating an evaporated film with a barrier paint, and hasmoisture barrier characteristics in terms of water vapor transmissionrate of 0.001 to 100 g/m²/day, the barrier capability of the firstpackaging material and of the second packaging material can bedetermined to be substantially equal, and the moisture-proof capabilityof the transparent barrier film can be selected according to requiredmoisture absorption capability. The packaging bag capable of maintaininghigh moisture-proof capability, therefore, can be provided.

When the light-reflective film is a film having a metallic luster thatcomprises an aluminum laminate film, an aluminum-evaporated film, aninorganic-evaporated film, or an inorganic oxide-evaporated film, or thelight-absorbing film comprises a film coated with or containing alight-absorbing material or a film laminate having a film coated with orlaminated with a light-absorbing material, and the light-reflective orlight-absorbing film has a water vapor transmission rate of 0.001g/m²/day to 100 g/m²/day, the light-absorbing or light-reflective filmcreates a greater color difference between the pattern printed layeroverlaid on the bag interior side and the moisture absorption indicatorpattern. As a result, the visibility of the moisture absorptionindicator pattern is fine when light permeability increases as a resultof moisture absorption by the desiccant-containing resin film. Inaddition, the barrier capability of the first packaging material and ofthe second packaging material can be determined to be substantiallyequal, and the moisture-proof capability of the transparent barrier filmcan be selected according to required moisture absorption capability.Thus, the packaging bag capable of maintaining high moisture-proofcapability can be provided.

When the pattern printed layer comprises a polyolefin film that isprovided on the desiccant-containing resin film or on thelight-reflective or light-absorbing film, and the moisture absorptionindicator pattern is a pattern including a character, numeral, design ora mixture thereof appropriately combined, which is printed at least onone surface of the polyolefin film, or when the pattern printed layer isprovided on the desiccant-containing resin film or on thelight-reflective or light-absorbing film, and the moisture-absorbingindicator pattern may be a pattern including a character, numeral, anddesign or a mixture thereof appropriately combined, which is printed atleast on one surface of the desiccant-containing resin film or of thelight-reflective or light-absorbing film, the desiccant-containing resinfilm becomes transparent as moisture absorption by a desiccant containedin desiccant-containing resin film approaches saturation, so that themoisture absorption indicator pattern can be visually recognized fromthe outside of the packaging bag once the desiccant reaches its moistureabsorption limit. This offers an advantage of facilitating themanagement of contents for protection from moisture. The moistureabsorption indicator pattern indicates the limit of preservation of anarticle. The moisture absorption indicator pattern, for example, may bea written expression “reaching the preservation limit”, a combination ofsuch an expression with designs, or a combination of characters,numerals, etc., having different print densities that can be visuallyrecognized in the order of a degree of density to allow a check on thepreservation limit step by step. Such a moisture absorption indicatorpattern is effective in managing the contents. The pattern printed layermay be provided with a printed layer having a background color that isformed on the outer surface of the pattern printed layer, which outersurface is opposite to the surface bearing the moisture absorptionindicator pattern. This increases an optical density difference toimprove visual recognition of the moisture absorption indicator pattern.

When the desiccant-containing resin film contains at least one or moreof substances selected from zeolite, silica gel, and alumina as adesiccant, the desiccant can be properly selected from these substancesaccording to a use, and the selection can be made to adopt a substancenot harmful to the human body. The transparency of thedesiccant-containing resin film is enhanced when the moistureabsorptiveness of the desiccant-containing resin film reachessaturation, and the light-reflective film or light-absorbing film isoverlaid on the outside of the desiccant-containing resin film in thesecond packaging material to ensure sufficient optical densitydifference. This results in an advantage that the desiccant-containingresin film does not prevent recognition of the moisture absorptionindicator pattern even if this film slightly colored as long as thedesiccant-containing resin film retains transparency when reachingsaturation in its moisture absorptiveness. When the desiccant-containingresin film contains an absorbent made of calcium oxide, calciumchloride, sulfate compound, barium oxide, activated carbon, claycompound, etc., to an extent that does not damage the effect of thepresent invention, the desiccant-containing resin film comes to haveincreased purpose-oriented absorbing capability.

When both first and second packaging materials are provided with thedesiccant-containing resin film and the moisture-proof capability of thefirst packaging material is lower than that of the second packagingmaterial, the desiccant-containing resin film on the first packagingmaterial becomes transparent first to allow visual recognition of astored article, and then the desiccant-containing resin film on thesecond packaging material gradually becomes transparent to allow visualrecognition of the moisture absorption indicator pattern on theunderlayer of the desiccant-containing resin film. Forming thedesiccant-containing resin film on both first and second packagingmaterials allows the maintenance of moisture absorption capability for along time, and enables the moisture-proof management of a stored articleon a step by step basis.

When the first packaging material or the second packaging material isformed into a shape having storage portions at least at two locations,the moisture absorption condition of a compound, etc., in the storageportion can be checked in such a case where the compound, etc., which ismoisture-degradable, is mixed with a liquid just before the actual useof a resulting mixture.

When the first packaging material is arranged to be at the front side ofan article stored in the packaging bag and the second packaging bag isarranged to be at the back side of the article, a case is preventedwhere the moisture absorption indicator pattern covers the surface ofthe stored article to make impossible checking on the stored article orspoil the design of the packaging bag.

When the light-absorbing film is a film printed with black ink, or is afilm made of a thermoplastic resin having carbon black mixed therein,the contrast of color of the moisture absorption indicator pattern tothat of the pattern printed layer is emphasized to enhance thevisibility of the pattern.

When the desiccant-containing resin film is mixed or coated with alight-scattering material, or the transparent barrier film is coatedwith a light-scattering material, the visibility of the moistureabsorption indicator pattern is further enhanced when the moistureabsorptiveness of the desiccant in the desiccant-containing resin filmreaches saturation. The light-scattering material should preferably besuch a globular substance as glass beads, silica, and acryl beads.

A drying agent with a moisture-absorbing indicator function according tothe present invention comprises an indicator film layer including abarrier film, a pattern printed layer having a moisture absorptionindicator pattern printed thereon, and a moisture-absorbing film thatbecomes transparent due to moisture absorption, the pattern printedlayer and moisture-absorbing film being laminated in this order on thebarrier film. The drying agent further includes a main desiccant layerand a moisture permeable layer that are provided on themoisture-absorbing film of the indicator film layer. This configurationoffers an advantage that the moisture absorption indicator pattern ofthe pattern printed layer is made visually recognizable through theacquirement of transparency by the moisture-absorbing film due tomoisture absorption without using cobalt chloride containing a heavymetal that is a substance harmful to the human body, and that themoisture absorption condition of the main desiccant layer can beindicated by the recognizable indicator pattern. The configuration alsooffers an advantage that the pattern printed layer for the moistureabsorption indicator is formed on one side of the moisture-absorbingfilm, and is coated with the barrier film to allow indication of thecondition of moisture absorption from the main desiccant layer side.

When the moisture absorptiveness of the main desiccant layer reachessaturation, the moisture absorptiveness of a desiccant mixed into themoisture-absorbing film also reaches saturation to make the desiccanttransparent, which allows visual recognition of the moisture absorptionindicator pattern from the outside of the drying agent. This dryingagent offers an advantage that just putting the drying agent into acontainer, etc., facilitates management of a stored article in thecontainer in protection from moisture. The moisture absorption indicatorpattern indicates the limit of preservation of an article, and may be,for example, a written expression “reaching the preservation limit”, acombination of such an expression with designs, or a combination ofcharacters, numerals, etc., having different print densities that can bevisually recognized in the order of a degree of density to allow a checkon the preservation limit step by step. This enables effectivemanagement of a content article.

In one embodiment, a moisture permeability control film may be overlaidon the moisture-absorbing film, the moisture permeability control filmcontrolling a time for the moisture absorptiveness of themoisture-absorbing film to take to reach saturation. According to thisembodiment, the moisture permeability control film serves as aninterposed film, enabling such control that moisture passing through themoisture permeable film is absorbed first by the main desiccant layer,and, after the moisture absorptiveness of the main desiccant layer hasreached saturation, the moisture-absorbing film is saturated withmoisture passing through the moisture permeability control film. Theindicator pattern, therefore, becomes visually recognizable after themoisture absorptiveness of the main desiccant layer has reachedsaturation.

When a space is formed between the main desiccant layer and themoisture-absorbing film or between the main desiccant layer and themoisture permeability control film to provide a bag-like portion, asheet bearing an indication of a desiccant can be stored in the bag-likeportion.

When the main desiccant layer is a transparent desiccant film, the maindesiccant layer is formed into a shape of a film or sheet. When the maindesiccant layer is a transparent desiccant molded body, the maindesiccant layer is formed into a desired shape of a plate, stick, etc. Adrying agent that is shaped in accordance with such a shape of thedesiccant is stored in a container or package of various shapes, wherethe drying agent can indicate drying capability in the container orpackage.

When the peripheries of the moisture permeable film and themoisture-absorbing film or of the moisture permeable film and themoisture permeability control film are sealed together to form abag-like portion, and a granular or tabular desiccant or a deliquescentdesiccant is enclosed in the bag-like portion to provide the maindesiccant layer, the drying agent comes to have improved moistureabsorption capability.

When the moisture-absorbing film comprises a laminate formed of adesiccant-containing resin layer and a thermoplastic resin, themechanical strength of the moisture-absorbing film becomes sufficientand the surface smoothness of the moisture-absorbing film is improved.

When a desiccant mixed into the moisture-absorbing film contains atleast one or more substances selected from zeolite, silica gel, andalumina, the desiccant does not have a negative effect on the human bodywhen it is disposed of in the living environment.

When the moisture permeability control film is a transparent film thathas a water vapor transmission rate of 0.01 to 5,000 g/m²/day, themoisture absorption capability required as the drying agent can bedetermined desirably through the moisture permeability control film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) is a partially cutout perspective view of one embodiment of apackaging bag with a moisture absorption indicator function according tothe present invention, and FIG. 1( b) is a partially cutout perspectiveview of the packaging bag on which a moisture absorption indicatorpattern has appeared when the moisture absorptiveness of a desiccant ofa desiccant-containing resin film has reached saturation.

FIGS. 2( a) to 2(d) are schematic sectional views of respective forms ofa first packaging material and a second packaging material according tothe embodiment of FIGS. 1( a) and 1(b).

FIG. 3( a) is a partially cutout perspective view of another embodimentof the packaging bag with a moisture absorption indicator functionaccording to the present invention, and FIG. 3( b) is a partially cutoutperspective view of the packaging bag on which the moisture absorptionindicator pattern has appeared when the moisture absorptiveness of thedesiccant of the desiccant-containing resin film has reached saturation.

FIGS. 4( a) and 4(b) are schematic sectional views of respective formsof the first packaging material and the second packaging materialaccording to the embodiment of FIGS. 3( a) and 3(b).

FIG. 5 is a sectional view of one embodiment of a drying agent with amoisture absorption indicator function according to the presentinvention.

FIG. 6 is a sectional view of another embodiment of the drying agentwith a moisture absorption indicator function according to the presentinvention.

FIGS. 7( a) and 7(b) are respective sectional views of furtherembodiments of the drying agent with a moisture absorption indicatorfunction according to the present invention, which drying agent has abag-like portion.

FIGS. 8( a) and 8(b) are respective sectional views of still furtherembodiments of the drying agent wherein a desiccant is stored in thebag-like portion.

FIG. 9 is a perspective view of the embodiment of FIG. 8( b).

FIG. 10 is a schematic sectional view of a conventional drying agentwith a moisture absorption indicator function.

FIG. 11 is a schematic sectional view of a conventional package having amoisture absorption indicator function.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of a packaging bag with a moisture absorption indicatorfunction according to the present invention will now be described withreference to the drawings. In describing the embodiments of thepackaging bag with the moisture absorption indicator function accordingto the present invention, the packaging bag is described as a packagingbag with a film having a drying function, which film is provided on thefront side of the packaging bag (front side of a stored article), and isdescribed as a separate packaging bag with a film having a dryingfunction, which film is not provided on the front side but on the backside of the packaging bag (back side of a stored article).

FIGS. 1( a) and 1(b) are partially cutout perspective views of oneembodiment of the packaging bag with the moisture absorption indicatorfunction according to the present invention. FIG. 1( a) shows a state ofmaintenance of moisture absorptiveness in the packaging bag, and FIG. 1(b) shows a state of saturation of moisture absorptiveness in thepackaging bag, where a moisture absorption indicator pattern 30 can bevisually recognized. The packaging bag of this embodiment includes afirst packaging material 10 on the front side of the packaging bag,which packaging material 10 has a desiccant-containing resin film, and asecond packaging material 20. The peripheries of the first and secondpackaging materials 10 and 20 are sealed together with a heat sealportion 40 to form a four-side sealed bag. An article A is stored in aspace (bag interior) between the first packaging material 10 and thesecond packaging material 20. This embodiment offers various forms shownin FIGS. 2( a) to 2(d). Each of the packaging bags in these variousforms is a packaging bag with a moisture absorption indicator functionhaving moisture-proof capability, which is made by heat sealing threesides of the first and second packaging materials 10 and 20 to join themtogether, each packaging material being cut into a rectangular shape ofa desired size, storing the article A in the joined package, then heatsealing the remaining one side of the first and second packagingmaterials 10 and 20 to complete a hermetic package.

Respective preferred forms of FIGS. 2( a) to 2(d) will be described inorder. According to the form of FIG. 2( a), the packaging bag includesthe first packaging material 10 and the second packaging material 20.The first packaging material 10 is a film laminate formed of adesiccant-containing resin film 11 and a transparent barrier film 12.The transparent barrier film 12 covers the outermost side of the firstpackaging material 10. The second packaging material 20 is a filmlaminate formed of a thermoplastic resin film (sealant film) 22, apattern printed film 23, and a light-reflective or light-absorbing film24. The desiccant-containing resin film 11 is made of a resincomposition containing zeolite, and one or both surfaces of thedesiccant-containing resin film 11 is/are laminated with polyolefin(e.g., LLDPE) by a coextrusion process when the desiccant-containingresin film 11 is molded. Laminating one or both surfaces of thezeolite-containing resin composition with a polyolefin resin layerimproves the strength of the first packaging material 10, and gives thezeolite-containing resin composition a flat film surface, whichemphasizes the transparency of the transparent barrier film 12.

The transparent barrier film 12 of the first packaging material 10 ismade of a polyester film, for example, it is made of a polyethyleneterephthalate (PET) film. The transparent barrier film 12 shouldpreferably be made of a film having a barrier property against watervapor or gas, such as a silica- or alumina-evaporated film, filmsputtered with a nitride, K-coated film (film coated with vinylidenechloride-vinyl chloride copolymer latex), OPP film (biaxially orientedpolypropylene film), or OPE film (oriented polyethylene film). Thetransparent barrier film 12 may also be made of a coextruded film, anengineering plastic film such as polyimide, polycarbonate, PPS(polyphenylene sulfide) or PES (polyether sulfide), a fluorocarbon resinfilm such as PTFE (polytetrafluoroethylene), or the like. Thetransparent barrier film 12 should desirably have moisture barriercharacteristics in terms of water vapor transmission rate of 0.001 to100 g/m²/day.

The desiccant-containing resin film 11 is manufactured in the followingway. First, a base resin is mixed with 5 to 80% of zeolite by weight andformed into a film shape after adding an additive, such as anethylene-acrylic ester-maleic anhydride copolymer or the like, at amixture ratio of 1 to 20% by weight to enhance an affinity of the baseresin and zeolite. In forming the desiccant-containing resin film, oneor both surfaces of the zeolite-containing resin are laminated withpolyolefin (e.g., LLDPE) by the coextrusion process. This is done forthe following reason. A single zeolite film, which substantiallyconsists of the base resin and the zeolite, has a rough film surfacebecause the base resin and zeolite are in a mixed state at the filmsurface, and the rough film surface lowers light transmittance. Thezeolite film as a single body shows an extremely high absorption rate inabsorbing moisture in the air to have difficulty in controlling asaturation reaching time, and is inferior in film strength as well. Todeal with this problem, the zeolite film is laminated with a film madeof polyolefin, etc., by the coextrusion process. This enhances thestrength of the film as a whole, reduces the surface roughness of thefilm, inhibits the separation of zeolite crystal aggregate, and exertsan effect of emphasizing the acquirement of transparency by the zeolitefilm due to moisture absorption. In addition, film lamination enablescontrol of a moisture absorption rate in accordance with the materialand thickness of the film. The polyolefin used here is transparent. Themixture ratio of zeolite should preferably be about 40 to 80% by weight,and further preferably be about 50 to 80% by weight.

The base resin is provided as a thermoplastic resin, for which one ormore resins are selected from, for example, LDPE (low densitypolyethylene), LLDPE (linear low density polyethylene), PP(polypropylene), and various copolymers, such as ionomer, EAA, EMAA,EVA, EEA, EMA, EMMA, etc. and are used alone or in a mixture form. Theselection from such resins is made so as to include a resin having ahigh MFR (melt flow rate), preferably having an MFR of 10 (g/10 minutes)or higher as measured under the conditions of a temperature of 190° C.and a load of 21.18 N.

Zeolite is a powdered inorganic porous substance having a pore diameterof 3 to 10 Å, and is used as a preferable absorbent. A zeolite having anaverage particle diameter of, for example, about 10 μm is preferable.The zeolite is a porous particulate substance with polarity that is usedto separate substances depending on a size of a molecule, and has astructure with uniform fine pores, so that the zeolite absorbs smallmolecules entering the cavities of the fine pores to act as a kind ofsieve. In addition to the zeolite, the desiccant may also contain atleast one or more of substances selected from calcium oxide, silica gel,calcium chloride, sulfate compound, barium oxide, alumina, activatedcarbon, and clay compound, but should preferably be made of a syntheticor natural zeolite.

The second packaging material 20 will now be described. The secondpackaging material 20 is a film laminate located at the back side of thestored article A. The second packaging material 20 includes thethermoplastic resin film 22 on the bag interior side thereof, thepattern printed film 23, and the light-reflective or light-absorbingfilm 24. The pattern printed film 23 and light-reflective orlight-absorbing film 24 are laminated in this order on the outer surfaceside of the thermoplastic resin film 22. The thermoplastic resin film 22may be laminated following lamination of the pattern printed film 23 andlight-reflective or light-absorbing film 24, or these three films may belaminated by using the coextrusion method.

As the thermoplastic resin film 22, one or more resins is/are selectedfrom LDPE (low density polyethylene), LLDPE (linear low densitypolyethylene), PP (polypropylene), PS (polystyrene), PMMA (polymethylmethacrylate), nylon, polyester (PET, PBT, PEN), PAN(polyacrylonitrile), and various copolymers such as ionomer, EAA, EMAA,EVA, EVOH, EEA, EMA, EMMA, etc, and is used alone or are used as in amixture form. Fluorocarbon resins, such as PTFE, can also be used. Forthe formation of the thermoplastic resin film 22, a preferable materialis selected when the first packaging material 10 and second packagingmaterials 20 are bonded and heat sealed together at their peripheries toform a hermetical package.

The pattern printed film 23 is made of, for example, a polyolefin filmto enhance the mechanical strength of the second packaging material 20.The pattern printed film 23 has the moisture absorption indicatorpattern 30 printed on one surface thereof, which indicator pattern 30serves as a humidity indicator. The moisture absorption indicatorpattern 30 is printed on the surface of the pattern printed film 23 thatis stuck to the thermoplastic resin film 22. The ink used for printingthe moisture absorption indicator pattern 30 contains a pigment or dyeat a weight ratio to the resin of 0.01 to 200% by weight, and has a filmthickness of 0.3 to 100 μM.

The light-reflective or light-absorbing film 24 is provided as either alight-reflective film or a light-absorbing film, and is formed to createa clear optical density difference with regard to the moistureabsorption indicator pattern 30. The light-reflective film 24 is made ofa metal foil or metal evaporated film having light reflectivity, such asan aluminum foil, aluminum-evaporated film, tin foil, tin-evaporatedfilm, nickel foil, or the like.

The light-absorbing film 24 is made of a film printed with black ink orof a film molded from a thermoplastic resin having carbon black mixedtherein. The surface of the pattern printed film 23 that is opposite tothe surface bearing the moisture absorption indicator pattern 30 may bepainted with ink having a color of any one or a mixture of white, black,red, blue, green, yellow, indigo, cyan, and magenta, which colorfunctions as a background color for the moisture absorption indicatorpattern 30, so that the pattern printed film 23 serves also as thelight-absorbing film 24. This background color provides a clear opticaldensity difference at the time of visual recognition of the moistureabsorption indicator pattern 30, and the tint of the background color isdetermined in view of the tint of the moisture absorption indicatorpattern 30. Obviously, the light-absorbing film 24 may be painted withink having a color of any one or a mixture of white, black, red, blue,green, yellow, indigo, cyan, and magenta.

In the packaging bag of this embodiment, the first packaging material 10is in a whitish turbid state before moisture absorption by thedesiccant-containing resin film 11 thereof when the article A is storedin the packaging bag, as shown in FIG. 1( a). The stored article A andthe moisture absorption indicator pattern 30, therefore, cannot bevisually recognized from the outside at the side of the first packagingmaterial 10. As the desiccant of the desiccant-containing resin film 11absorbs moisture to cause the moisture absorption capability of thedesiccant to approach saturation, the desiccant-containing resin film 11gradually turns transparent to allow the visual recognition of thestored article A and of the moisture absorption indicator pattern 30 aswell. When the moisture absorptiveness of the desiccant of thedesiccant-containing resin film 11 reaches saturation completely, thedesiccant-containing resin film 11 becomes transparent substantially, asshown in FIG. 1( b), which allows visual recognition of the storedarticle A and of the moisture absorption indicator pattern 30 printed as“KP” on the inner surface of the second packaging material 20.

The moisture absorption indicator pattern 30 is provided as printedcharacters of “KP” in FIG. 1( b), but may be provided as a printedpattern of numerals, designs, or a mixture thereof appropriatelycombined. As the desiccant contained in the desiccant-containing resinfilm 11 absorbs moisture to approach saturation in moisture absorption,the transparency of the desiccant-containing resin film 11 graduallyincreases, so that the moisture absorption indicator pattern 30 canobviously be recognized directly by unsealing the packaging bag, and canalso be visually recognized from the outside of the packaging bagwithout unsealing. The moisture absorption indicator pattern 30indicates the limit of preservation of the stored article A, and may bea written expression “reaching the preservation limit”, or a combinationof such an expression with designs, or a combination of characters,numerals, etc., having different print densities that can be visuallyrecognized in the order of a degree of density according to a change inthe transparency of the desiccant-containing resin film 11; that is, anextent of moisture absorption by the desiccant, to allow a check on thepreservation limit step by step. This enables effective moisture-proofmanagement for the stored article A.

According to this embodiment, when a pinhole is present on thelight-reflective or light-absorbing film 24 or on the transparentbarrier film 12, external moisture infiltrates into the packaging bagthrough the pinhole to cause the moisture absorption capability of thedesiccant of the desiccant-containing resin film 11 to reach saturationin a relatively short time, thus causing the desiccant-containing resinfilm 11 to become partially or wholly transparent to allow visualrecognition of the moisture absorption indicator pattern 30. Thisphenomenon enables a user to make a determination that the packaging bagdoes not function as a moisture-proof bag.

The embodiment of FIG. 2( b) will now be described. The same componentsas described in the above embodiment will be denoted by the samereference numerals as those denoting such components in the aboveembodiment. According to this embodiment, both first and secondpackaging materials 10 and 20 are provided with the desiccant-containingresin film in such a way that the desiccant-containing resin film 11 isformed on the bag interior side of the first packaging material 10, andthat another desiccant-containing resin film 21 is formed on the baginterior side of the second packaging material 20. On the outside of thedesiccant-containing resin film 21 of the second packaging material 20,the pattern printed film 23 having the moisture absorption indicatorpattern 30 printed thereon and the light-reflective or light-absorbingfilm 24 are laminated in this order. The desiccant-containing resin film21 of the second packaging material 20 is the same as thedesiccant-containing resin film 11 according to the embodiment of FIG.2( a).

According to this embodiment, the first packaging material 10 and thesecond packaging material 20 are provided with the desiccant-containingresin film 11 and the desiccant-containing resin film 21, respectively,so that the moisture absorption indicator pattern 30 cannot be visuallyrecognized until the moisture absorption capability of desiccantscontained in the desiccant-containing resin films 11 and 21 reachsaturation. To ensure the fine visibility of the moisture absorptionindicator pattern 30, an optical density difference with regard to themoisture absorption indicator pattern 30 must be enlarged. For thisreason, the pattern printed film 23 should desirably be laminated on theoutside thereof with the light-reflective film 24, which is made of analuminum foil laminated film, etc., that has high reflectivity. Sincethe first packaging material 10 and the second packaging material 20 areprovided with the respective desiccant-containing resin films 11 and 21,the whole of the inner side of the packaging bag is covered with thedesiccant-containing resin films. As a result, the packaging bag canmaintain its function as the moisture-proof bag for a longer time thanin the case of the embodiment of FIG. 2( a), except that it partiallydepends on the capability of the transparent barrier film 12.

The embodiment of FIG. 2( c) will now be described. The same componentsas described in the above embodiment will be denoted by the samereference numerals as those denoting such components in the aboveembodiment. According to this embodiment, the first packaging material10 is a laminate formed of the transparent barrier film 12 and thedesiccant-containing resin film 11. The second packaging material 20includes the thermoplastic resin film 22 provided on the bag interiorside of the second packaging material 20, and also includes the patternprinted film 23 having the moisture absorption indicator pattern 30printed thereon, the light-reflective or light-absorbing film 24, andthe transparent barrier film 25 that are laminated in this order on theoutside of the thermoplastic resin film 22. According to thisembodiment, the outermost side of the packaging bag is laminated withthe transparent barrier films 12 and 25, which provides the packagingbag that is capable of maintaining the moisture absorption capability ofthe desiccant-containing resin film 11 for a long time.

The barrier film 25 of the second packaging material 20 of thisembodiment should preferably be a gas barrier film, and does notnecessarily have to be transparent. For example, the barrier film 25 ismade of an aluminum laminate film, a metal evaporated film such asaluminum-evaporated film, inorganic-evaporated film, or inorganicoxide-evaporated film, a K-coated film (film coated with vinylidenechloride-vinyl chloride copolymer latex), an OPP film (biaxiallyoriented polypropylene film), or an OPE film (oriented polyethylenefilm). The barrier film 25 may also be made of a coextruded film, anengineering plastic film such as polyimide, polycarbonate, PPS(polyphenylene sulfide), or PES (polyether sulfide), or a fluorocarbonresin film such as PTFE (polytetrafluoroethylene). Covering bothsurfaces of the first and second packaging films 10 and 20 with thebarrier films enables control of the saturation reaching time of themoisture absorption capability of the desiccant-containing resin films11 and 21, for example, in a range of 1 day to 100 days or longer. Whenthe barrier capability of the first packaging material 10 and of thesecond packaging material 20 is determined to be substantially equal,and the moisture-proof capability of the transparent barrier films 12and 25 is selected according to required moisture absorption capability,the packaging bag capable of semipermanently maintaining moisture-proofcapability can be provided.

The transparent barrier film 12 of the first packaging material 10 inthis embodiment is the same as the transparent barrier film 12 describedin the above embodiment. The transparent barrier film 12 of the firstpackaging material 10 cannot be made of such a light-reflective film asaluminum laminate film because of a demand for transparency, but can bemade of a film that is provided with a silica- or alumina-evaporatedfilm, a multilayer-evaporated film of silica and alumina, a siliconnitride-evaporated film, a coating layer of a barrier paint, or a layermade by coating an evaporated film with a barrier paint. The transparentbarrier film 12 has moisture barrier characteristics in terms of watervapor transmission rate of 0.001 to 100 g/m²/day.

The embodiment of FIG. 2( d) will now be described. The same componentsas described in the above embodiment will be denoted by the samereference numerals. According to this embodiment, the first packagingmaterial 10 and the second packaging material 20 are provided with thetransparent barrier film 12 and the transparent barrier film 25,respectively, and also with the desiccant-containing resin film 11 andthe desiccant-containing resin film 21, respectively. Thedesiccant-containing resin films 11 and 21 in this embodiment are thesame as the desiccant-containing resin film described in the aboveembodiment, and are each coated with a polyolefin resin on both surfacesthereof. On the outside of the desiccant-containing resin film 21 of thesecond packaging material 20, the pattern printed film 23 having themoisture absorption indicator pattern 30 printed thereon, thelight-reflective or light-absorbing film 24, and the transparent barrierfilm 25 are laminated in this order.

According to this embodiment, the outermost surfaces of the firstpackaging material 10 and the second packaging material 20 of thepackaging bag are laminated with the transparent barrier film 12 and thetransparent barrier film 25, respectively. Because of this, thedesiccant-containing resin films 11 and 21 can maintain their moistureabsorption capability for a longer time than in the case of theembodiment of FIG. 2( b). The first packaging material 10 and the secondpackaging material 20 have the desiccant-containing resin films 11 and21, respectively, which slightly deteriorates the visibility of themoisture absorption indicator pattern 30. For this reason, thelight-reflective film 24 made of an aluminum foil laminated film, etc.,should preferably be overlaid on the outside surface of the patternprinted film 23 to enlarge an optical density difference. Coating thesurfaces of the desiccant-containing resin films 11 and 21 with thepolyolefin resin improves the visibility.

Another embodiment of the packaging bag with a moisture absorptionindicator function according to the present invention shown in FIGS. 3(a) and 3(b) will now be described. FIGS. 3( a) and 3(b) are partiallycutout perspective views of the packaging bag of this embodiment. Theperipheral four sides of the first and second packaging materials 10 and20 are sealed together with the heat seal portion 40, and the article Ais stored in the packaging bag interior 45. Examples of this embodimentare depicted in FIGS. 4( a) and 4(b). This embodiment is different fromthe embodiment of FIGS. 2( a) to 2(d) in the point that the firstpackaging material 10 is a transparent laminated film, and that thedesiccant-containing resin film 21 is included in the second packagingmaterial 20. As shown in FIG. 3( a), the stored article A can berecognized from the outside of the packaging bag. FIG. 3( a) depicts astate of maintenance of the moisture absorption capability of thedesiccant-containing resin film 21, in which state the moistureabsorption indicator pattern 30 on the bag interior side of the secondpackaging material 20 cannot be recognized. In a state shown in FIG. 3(b), on the other hand, the moisture absorption indicator pattern 30 canbe recognized. FIG. 3( b), therefore, depicts the complete saturation ofmoisture absorption capability of the desiccant-containing resin film21.

Embodiments of FIGS. 4( a) and 4(b) will now be described. The samecomponents as described in the above embodiment will be denoted by thesame reference numerals. According to the embodiment of FIG. 4( a), thefirst packaging material 10 is a laminated film formed of thetransparent barrier film 12 that is the outermost layer of the packagingbag, and a thermoplastic resin film (sealant film) 13. The secondpackaging film 20 includes the desiccant-containing resin film 21, thepattern printed film 23 printed with the moisture absorption indicatorpattern 30, the pattern printed film 23 being overlaid on the outside ofthe desiccant-containing resin film 21, and the light-reflective orlight-absorbing layer 24 that is overlaid on the pattern printed film23. The thermoplastic resin film 13 is the same as the thermoplasticresin film 22 in the embodiment of FIG. 2( a) or 2(c), and is selectedas a material having a fine sealing property.

According to the embodiment of FIG. 4( b), the first packaging material10 is the laminated film formed of the transparent barrier film 12 thatis the outermost layer, and the thermoplastic resin film (sealant film)13. The second packaging material 20 includes the desiccant-containingresin film 21, the pattern printed film 23 printed with the moistureabsorption indicator pattern 30, the light-reflective or light-absorbinglayer 24, and the transparent barrier film 25, the pattern printed film23, light-reflective or light-absorbing layer 24, and transparentbarrier film 25 being laminated in this order on the outside of thedesiccant-containing resin film 21. According to this embodiment, theoutermost layer of the packaging bag is covered with the barrier films12 and 25. The barrier film 12 of the first packaging material 10 istransparent, but the barrier film 25 of the second packaging material 20does not necessarily have to be transparent. The barrier film 25 isacceptable when having a fine barrier property against water vapor.

In each of the embodiments of FIGS. 4( a) and 4(b), the second packagingmaterial 20 is provided with the desiccant-containing resin film 21,which has a whitish turbid appearance. When the desiccant of thedesiccant-containing resin film 21 absorbs moisture to reach saturation,however, the desiccant-containing resin film 21 changes its appearancefrom white into transparent. As a result, the moisture absorptionindicator pattern 30 of the pattern printed film 23 can be visuallyrecognized through the desiccant-containing resin film 21 of the secondpackaging material 20, which desiccant-containing resin film 21 hasturned transparent.

In each of the embodiments of FIGS. 4( a) and 4(b), in the same manneras in the above embodiment, the desiccant-containing resin film 21 ismade of a resin composition containing zeolite, and is laminated withpolyolefin (e.g., LLDPE) on one or both surfaces of thedesiccant-containing resin film 21 by the coextrusion method.

In a case where the transparent barrier film 25 of the second packagingmaterial 20 is made of a polyester film, laminating the second packagingmaterial 20 with the transparent barrier film 25 enables control ofmoisture absorption from one or both surfaces because the transparentbarrier film 25 has a barrier property against moisture permeation. Thetransparent barrier film 12 of the first packaging material 10 shouldpreferably be a gas barrier transparent film such as aninorganic-evaporated film, an inorganic oxide-evaporated film, aK-coated film (film coated with vinylidene chloride-vinyl chloridecopolymer latex), an OPP film (biaxially oriented polypropylene film),or an OPE film (oriented polyethylene film). The transparent barrierfilm 12 may also be made of a coextruded film, an engineering plasticfilm such as polyimide, polycarbonate, PPS (polyphenylene sulfide), orPES (polyether sulfide), or a fluorocarbon resin film such as PTFE(polytetrafluoroethylene). The transparent barrier film 12 is a filmthat is provided with a silica- or alumina-evaporated film, amultilayer-evaporated film of silica and alumina, a siliconnitride-evaporated film, a coating layer of a barrier paint, or a layermade by coating an evaporated film with a barrier paint. The transparentbarrier film 12 has moisture barrier characteristics in terms of watervapor transmission rate of 0.001 to 100 g/m²/day. Covering both outersurfaces of the first and second packaging materials 10 and 20 with thebarrier films enables control of the saturation reaching time ofmoisture absorptiveness of the desiccant-containing resin film 21according to moisture absorption capability demanded by the storedarticle A in a range of, for example, 1 day to 100 days or longer.

The packaging bag of the present invention is the packaging bag that isformed by heat sealing the peripheral four sides of the first and secondpackaging materials to provide one storage portion, as described in theabove embodiments. The packaging bag may be so formed as to, forexample, give the second packaging material a box-like or cylindricalshape, or as to provide two storage portions, which latter case enablespackaging of a pair of products consisting of a product requiringmoisture absorption capability and a product not requiring moistureabsorption capability. A heavy metal harmful to the human body is notused for surface treatment on the transparent barrier film, and as thematerial of the desiccant, either.

According to the present invention, the transparent barrier film may becoated with a globular light-scattering material such as glass beads,silica, or acryl beads or the desiccant-containing resin film may bemixed or coated with a light-scattering material to improve thevisibility of the indicator pattern.

Embodiments of a drying agent with a moisture absorption indicatorfunction according to the present invention will now be described withreference to the drawings.

One embodiment of the drying agent with a moisture absorption indicatorfunction according to the present invention will be described first withreference to FIG. 5. As shown in FIG. 5, the drying agent of the presentinvention includes an indicator film layer 70, a transparent desiccantfilm (main desiccant layer) 61 functioning as a main desiccant, whichtransparent desiccant film 61 is overlaid on the indicator film layer70, and a moisture permeable film 64 that is overlaid on the transparentdesiccant film 61. The indicator film layer 70 has a barrier film 75, apattern printed layer 73 for a moisture absorption indicator, and amoisture-absorbing film 71 containing zeolite, the pattern printed layer73 and moisture-absorbing film 71 being laminated on the barrier film 75in this order. The transparent desiccant film 61 is overlaid on themoisture-absorbing film 71 of the indicator film layer 70.

The barrier film 75 is a film that cuts off moisture infiltrating fromthe pattern printed layer 73 into the moisture-absorbing film 71, and ismade of a polyester film, for example, made of a polyethyleneterephthalate (PET) film. The barrier film 75 should preferably be madeof a film having a barrier property against water vapor or gas, such asa silica- or alumina-evaporated film, a film sputtered with a nitride, alaminate of an aluminum foil and a thermoplastic film, a K-coated film(film coated with vinylidene chloride-vinyl chloride copolymer latex),an OPP film (biaxially oriented polypropylene film), or an OPE film(oriented polyethylene film). The barrier film 75 may also be made of acoextruded film, an engineering plastic film such as polyimide,polycarbonate, PPS (polyphenylene sulfide), or PES (polyether sulfide),or a fluorocarbon resin film such as PTFE (polytetrafluoroethylene). Thebarrier film 75 should desirably have moisture barrier characteristicsin terms of water vapor transmission rate of 0.001 to 100 g/m²/day.

The pattern printed layer 73 is made by printing a moisture absorptionindicator pattern 80 on a thermoplastic resin film. The moistureabsorption indicator pattern 80 may be printed on the back face of themoisture-absorbing film 71 or on the upper surface of the barrier film75. The moisture absorption indicator pattern 80 of the pattern printedlayer 73 is a printed pattern including characters, numerals, designs,or a mixture thereof appropriately combined. The surface of patternprinted layer 73 that bears the moisture absorption indicator pattern 80may be painted with ink having a color of any one or a mixture of white,black, red, blue, green, yellow, indigo, cyan, and magenta, which colorfunctions as a background color for the moisture absorption indicatorpattern 80. This background color provides a clear optical densitydifference at the time of visual recognition of the moisture absorptionindicator pattern 80, and the tint of the background color is determinedin view of the tint of the moisture absorption indicator pattern 80. Theink used for printing the moisture absorption indicator pattern 80contains a pigment or dye at a weight ratio to the resin of 0.01 to 200%by weight, and has a film thickness of 0.3 to 100 μm.

The moisture-absorbing film 71 is made of a resin composition containinga desiccant, for example, zeolite mixed therein, which resin compositionis laminated with polyolefin (e.g. LLDPE) on one or both surfacesthereof by the coextrusion process when the moisture-absorbing film 71containing the zeolite is molded. Zeolite is a powdered inorganic poroussubstance having a pore diameter of 3 to 10 Å, and is used as apreferable absorbent. A zeolite having an average particle diameter of,for example, about 10 μm is preferable. The zeolite is a porousparticulate substance with polarity that is used to separate substancesdepending on a size of a molecule, and has a structure with uniformpores, so that the zeolite absorbs small molecules entering the cavitiesof the fine pores to act as a kind of a sieve. In addition to thezeolite, the desiccant contained in the moisture-absorbing film 71 mayalso contain at least one or more of substances selected from calciumoxide, silica gel, calcium chloride, sulfate compound, barium oxide,alumina, activated carbon, and clay compound, but should preferable bemade of a synthetic or natural zeolite.

The moisture-absorbing film 71 is manufactured in the following way.First, a base resin is mixed with 5 to 80% of zeolite by weight, andformed into a film shape after adding an additive, such as anethylene-acrylic ester-maleic anhydride copolymer, or the like at amixture ratio of 1 to 20% by weight to enhance an affinity of the baseresin and zeolite. In forming the zeolite-containing resin film, one orboth surfaces of the zeolite-containing resin are laminated withpolyolefin (e.g., LLDPE) by the coextrusion process. The mixture ratioof the zeolite should preferably be 40 to 80%, and further preferably be50 to 80% in terms of weight ratio. This gives the moisture-absorbingfilm high absorption capability, and enhances the effectiveness ofconcealment of the moisture absorption indicator pattern before moistureabsorption.

The base resin is provided as a thermoplastic resin, which is made ofone or more resins selected from, for example, LDPE (low densitypolyethylene), LLDPE (linear low density polyethylene), PP(polypropylene), and various copolymers such as ionomer, EAA, EMAA, EVA,EEA, EMA, EMMA, etc. and which is used alone or in a mixture form. Theselection from such resins is made so as to include a resin having ahigh MFR (melt flow rate), preferably having an MFR of 10 (g/10 minutes)or higher as measured under the conditions of a temperature of 190° C.and a load of 21.18 N.

The transparent desiccant film 61, which is the main desiccant layer, isa film made by mixing silicon dioxide (silica gel), which is a maindesiccant, into a thermoplastic resin. The silicon dioxide (silica gel)is the most preferable substance as the main desiccant, but the maindesiccant may also be made of fine powder of calcium oxide, calciumchloride, sulfate compound, barium oxide, etc.

In providing a modification of this embodiment, the transparentdesiccant film 61, which is the main desiccant layer, may be replacedwith a transparent desiccant molded body. This transparent desiccantmolded body is made by typically mixing silicon dioxide (silica gel)into a thermoplastic resin, and is molded using a molding die. Thetransparent desiccant molded body includes a molded body of a sheetshape, plate shape, stick shape, and even of a castable shape. Astick-shaped transparent desiccant molded body has, for example, arectangular section. The moisture permeable film 64 is overlaid on onesurface of the stick-shaped transparent desiccant molded body, and themoisture-absorbing film 71 of the indicator film layer 70 is overlaid onthe other surface of the same to be opposite to the moisture permeablefilm 64.

According to the above embodiment, the moisture absorption indicatorpattern 80 of the pattern printed layer 73 becomes visually recognizablefrom the outside of the drying agent as the moisture absorptioncapability of the transparent desiccant film 61 or the transparentdesiccant molded body approaches saturation. Being able to see themoisture absorption indicator pattern 80 from the outside, therefore,means that the absorption capability of the drying agent has reachedsaturation.

Another embodiment of the drying agent with a moisture-absorbingindicator function according to the present invention will now bedescribed with reference to FIG. 6. As shown in FIG. 6, according tothis embodiment, a moisture permeability control film 76 is interposedbetween the transparent desiccant film 61 or the transparent desiccantmolded body, which is the main desiccant layer of the above embodiment,and the moisture-absorbing film 71. The moisture permeability controlfilm 76 is a transparent film, and is made of, for example, polyethyleneterephthalate (PET), which is a thermoplastic resin. The moisturepermeability control film 76 may be made of another kind of athermoplastic resin, such as polyethylene (PE), polypropylene (PP),polyvinyl chloride (PVC), nylon (Ny), ethylene vinyl acetate (EVA),polystyrene (PS), ethylene-vinyl alcohol copolymer (EVOH), orpolyvinylidene chloride (PVDC). Also, the moisture permeability controlfilm 76 may be made of cellophane that has superior moistureabsorptiveness and moisture permeability.

The moisture permeability control film 76 made of the abovethermoplastic resin or cellophane functions as a protective film thatprevents the moisture absorption capability of the moisture-absorbingfilm 71 from saturating faster than the moisture absorption capabilityof the main desiccant while the moisture absorption capability of thetransparent desiccant film 61 or the transparent desiccant molded body,which is the main desiccant layer, continues working. The transparentdesiccant film 61 or the transparent desiccant molded body maintains themoisture absorption capability longer than the moisture-absorbing film71 does, so that covering the moisture-absorbing film 71 with themoisture permeability control film 76 enables control of a moistureabsorption capability maintenance time of the moisture-absorbing film71. Control of the maintenance time is carried out by properly selectingthe film thickness of the thermoplastic resin or cellophane and theinherent moisture absorption rate of such a material to determine themoisture permeability control film 76 to be used. The moisturepermeability control film 76 can be selected as a film having a watervapor transmission rate of 0.01 to 5000 g/m²/day. The use of themoisture permeability control film 76 offers an advantage of allowingthe drying agent with the moisture absorption indicator function todetermine moisture absorption capability required as the drying agent ina desirable manner.

FIGS. 7( a) and 7(b) depict further embodiments of the drying agent witha moisture absorption indicator function according to the presentinvention. According to the embodiment of FIG. 7( a), a bag-like portion65 is provided by forming a space between laminated layers. A sheetbearing an indication of a desiccant can be put in the bag-like portion65. According to the embodiment of FIG. 5, the indicator film layer 70is the laminate formed of the moisture-absorbing film 71, patternprinted layer 73, and barrier film 75, and the transparent desiccantfilm 61 and the moisture permeable film 64 are laminated in this orderon the moisture-absorbing film 71 of the indicator film layer 70. Incontrast, according to the embodiment of FIG. 7( a), the bag-likeportion 65 is formed between the moisture-absorbing film 71 and thetransparent desiccant film 61. According to this embodiment, a sheet ofthe indicator film layer 70 and a sheet of lamination of the transparentdesiccant film 61 and the moisture permeable film 64 are so heat sealedtogether at the peripheries of both sheets that the moisture-absorbingfilm 71 and the transparent desiccant film 61 face each other.

The embodiment of FIG. 7( b) corresponds to the embodiment of FIG. 6,and provides the bag-like portion 65 formed between the transparentdesiccant film 61 and the moisture permeability control film 76.According to the embodiment of FIG. 7( b), a sheet of lamination of themoisture permeable film 64 and the transparent desiccant film 61 and asheet of lamination of the indicator film 70 and the moisturepermeability control film 76 are so heat sealed together at theperipheries of both sheets that the transparent desiccant film 61 andthe moisture permeability control film 76 face each other. With respectto the embodiments of FIGS. 7( a) and 7(b), the sheet of lamination ofthe moisture permeable film 64 and the transparent desiccant film 61,and the sheet of the indicator film layer 70 or the sheet of laminationof the indicator film layer 70 and the moisture permeability controlfilm 76 are depicted as exaggerated curved shapes to give a clearpicture of the bag-like portion 65, but the drying agent as a wholeactually has the sheet-like outline.

Still further embodiments of the drying agent according to the presentinvention are shown in FIGS. 8( a), 8(b), and 9, which include thebag-like portion 65 filled with molded globular transparent silica gel66. According to the embodiment of FIG. 8( a), the bag-like portion 65is formed using the moisture-absorbing film 71 of the indicator filmlayer 70 and the moisture permeable film 64, and is filled with thesilica gel 66. According to the embodiment of FIG. 8( b), the bag-likeportion 65 is formed using a sheet of lamination of the indicator filmlayer 70 and the permeability control film 76 on the moisture-absorbingfilm 71 of the indicator film layer 70, and the moisture permeable film64, and is filled with the silica gel 66. The silica gel 66 istransparent, thus not facilitating a determination on whether thefunction of the silica gel 66 as the desiccant has been lost even whenmoisture absorption by the silica gel 66 reaches saturation. The silicagel 66 may be formed into a columnar shape or tabular shape. The patternprinted layer 73 is printed with the moisture absorption indicatorpattern 80, which is, for example, a printed pattern of “Kp”. Themoisture absorption indicator pattern 80 cannot be visually recognizedfrom the outside while the moisture absorption capability is maintained,but the printed pattern of “Kp” as the absorption indicator pattern 80can be visually recognized when the moisture absorptiveness of themoisture-absorbing film 71 reaches saturation, which indicates the lossof the function as the drying agent. The moisture absorption indicatorpattern 80 of the pattern printed layer 73 of this embodiment is thesame as the moisture absorption indicator pattern 80 described in theabove embodiment. The desiccant stored in the bag-like portion 65 doesnot have to be transparent, but instead can be nontransparent if thedesiccant becomes transparent at the point that the moistureabsorptiveness of the desiccant reaches saturation or if a part of thepattern printed layer 73 including the moisture absorption indicatorpattern 80 at the back of the desiccant can be visually recognized atthe point that the desiccant is stored in the bag-like portion 65.

The moisture absorption indicator pattern 80 is provided as printedcharacters “Kp”, etc., in FIG. 9, but may be provided as a printedpattern of numerals, designs, or a mixture thereof appropriatelycombined. As the desiccant contained in the moisture-absorbing film 71absorbs moisture to approach saturation in moisture absorption, thetransparency of the moisture-absorbing film 71 increases, which allowsvisual recognition of the moisture absorption indicator pattern 80. Themoisture absorption indicator pattern 80 may be a written expression“reaching the preservation limit”, or a combination of such anexpression with designs, or a combination of characters, numerals, etc.,having different print densities that can be visually recognized in theorder of a degree of density to allow visual recognition of a state ofmoisture absorption step by step.

While the bag-like portion 65 is filled with the silica gel 66functioning as the desiccant according to the embodiments of FIGS. 8( a)and 8(b), a deliquescent desiccant may also be used in place of thesilica gel 66. The deliquescent desiccant is provided as calciumchloride, magnesium chloride, potassium oxide, sodium oxide, alunite,magnesium sulfate, phosphorus oxide, etc. The deliquescent desiccantabsorbs moisture to become a transparent liquefied matter, through whichthe moisture absorption indicator pattern 80 can be visually recognized.These desiccants are acceptable if the desiccants turn transparent whentheir moisture absorption capability reaches saturation.

Example

Examples of the packaging bag according to the present invention will bedescribed. Materials used for the following examples will be describedfirst. A PETsio_(x) film, which is made by vapor depositing silica on aPET film, is used for a transparent barrier film. The PETsio_(x) film is12 μm in thickness, and is laminated with an LDPE (low densitypolyethylene) film of 40 μm in thickness to provide the transparentbarrier film. The transparent barrier film has a water vaportransmission rate of 0.1 g/m²/day, and corresponds to the transparentbarrier film 12 of the first packaging material 10 of the embodiments ofFIGS. 2( a) to 2(d), and 4(a) and 4(b).

A laminate of a transparent barrier film and a desiccant-containingresin film is the laminate that is formed of a transparent barrier filmmade of a PETsio_(x) film of 12 μm in thickness, and a film made bylaminating both surfaces of a desiccant-containing resin layer of 60 μmin thickness with an LDPE film of 10 μm in thickness. Thedesiccant-containing resin layer contains LDPE and zeolite at a weightratio of 1:1. The laminate of the transparent barrier film and thedesiccant-containing resin film has a water vapor transmission rate of0.2 g/m²/day, and corresponds to the first packaging material 10 of theembodiments of FIGS. 2( a) to 2(d).

An aluminum-evaporated film (PET_(AL)) is made by vapor depositingaluminum on a PET film to have a thickness of 50 μm. Thealuminum-evaporated film (PET_(AL)) has a water vapor transmission rateof 1.0 g/m²/day, and corresponds to the light-reflective film 24 of theembodiments of FIGS. 2( a) to 2(d), and 4(a) and 4(b).

A laminate of a light-absorbing film and a transparent barrier film isthe laminate that is formed of a light-absorbing film made by printing aPET film of 100 μm in thickness with black ink, and the abovetransparent barrier film. The laminate of the light-absorbing film andthe transparent barrier film has a water vapor transmission rate of 0.05g/m²/day, and corresponds to the light-absorbing film 24 and thetransparent barrier film 25 of the embodiments of FIGS. 2(C) and 2( d),and 4(b).

A laminate of an aluminum-evaporated film and a transparent barrier filmis the laminate that is formed of the above aluminum-evaporated film(PET_(AL)), and the above transparent film. The laminate of thealuminum-evaporated film and the transparent barrier film has a watervapor transmission rate of 0.02 g/m²/day, and corresponds to thelight-reflective film 24 and the transparent barrier film 25 of theembodiments of FIGS. 2(C) and 2( d), and 4(b).

An aluminum foil laminated film is made by laminating an aluminum foilof 9 μm in thickness with a PET film of 12 μm in thickness. The aluminumfoil laminated film has a water vapor transmission rate of 0.00g/m²/day, and corresponds to the light-reflective film 24 of theembodiments of FIGS. 2( a) and 2(b), and 4(a) and 4(b).

A pattern printed film is made by printing a moisture absorptionindicator pattern on a PET film of 25 μm in thickness, and correspondsto the pattern printed film 23 of the embodiments of FIGS. 2( a) to2(d), and 4(a) and 4(b).

A thermoplastic resin film is made of an LDPE film of 40 μm inthickness, has a water vapor transmission rate of 10 g/m²/day, andcorresponds to the thermoplastic film 22 or the sealant film 13 of theembodiments of FIGS. 2( a) and 2(c), and 4(a) and 4(b).

In example 1, the first packaging material 10 is a laminate formed ofthe transparent barrier film and the sealant film, and the secondpackaging material 20 is a laminate formed of the desiccant-containingresin film, the pattern printed film, and the aluminum foil laminatedfilm (FIG. 4( a)).

In example 2, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the sealant film, and the secondpackaging material 20 is a laminate formed of the desiccant-containingresin film, the pattern printed film, and the aluminum-evaporated film(FIG. 4( a)).

In example 3, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the sealant film, and the secondpackaging material 20 is a laminate formed of the desiccant-containingresin film, the pattern printed film, the aluminum-evaporated film, andthe transparent barrier film (FIG. 4( b)).

In example 4, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the sealant film, and the secondpackaging material 20 is a laminate formed of the desiccant-containingresin film, the pattern printed film, the light-absorbing film, and thetransparent barrier film (FIG. 4( b)).

In example 5, the first packaging material 10 is a laminate formed ofthe transparent barrier film and the desiccant-containing resin film,and the second packaging material 20 is the laminate formed of thedesiccant-containing resin film, the pattern printed film, the aluminumfoil laminated film (FIG. 2( b)).

In example 6, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the desiccant-containing resin film,and the second packaging material 20 is the laminate formed of thedesiccant-containing resin film, the pattern printed film, and thealuminum-evaporated film (FIG. 2( b)).

In example 7, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the desiccant-containing resin film,and the second packaging material 20 is the laminate formed of thedesiccant-containing resin film, the pattern printed film, thealuminum-evaporated film, and the transparent barrier film (FIG. 2( d)).

In example 8, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the desiccant-containing resin film,and the second packaging material 20 is the laminate formed of thedesiccant-containing resin film, the pattern printed film, thelight-absorbing film, and the transparent barrier film (FIG. 2( d)).

In example 9, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the desiccant-containing resin film,and the second packaging material 20 is a laminate formed of the sealantfilm, the pattern printed film, and the aluminum foil laminated film(FIG. 2( a)).

In example 10, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the desiccant-containing resin film,and the second packaging material 20 is a laminate formed of the sealantfilm, the pattern printed film, and the aluminum-evaporated film (FIG.2( a)).

In example 11, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the desiccant-containing resin film,and the second packaging material 20 is a laminate formed of the sealantfilm, the pattern printed film, the aluminum-evaporated film, and thetransparent barrier film (FIG. 2( c)).

In example 12, the first packaging material 10 is the laminate formed ofthe transparent barrier film and the desiccant-containing resin film,and the second packaging material 20 is a laminate formed of the sealantfilm, the pattern printed film, the light-absorbing film, and thetransparent barrier film (FIG. 2( c)).

Each pair of laminates according to each of examples 1 to 12 are cutinto a square shape 10 by 10 cm. The cut laminates are then superposedon one another as the first packaging material 10 and the secondpackaging material 20, and are heat sealed on four sides to make thepackaging bag. Subsequently, a time (days) for the moistureabsorptiveness of the desiccant of the desiccant-containing resin filmto take to reach saturation is determined by measuring a time for themoisture absorption indicator pattern to take to appear under atemperature of 40° C. and a relative humidity of 90%.

TABLE 1 Time (Days) for Moisture Absorptiveness of Desiccant ofDesiccant-Containing Resin Film to Take to Reach Saturation Example 1 80Example 2 10 Example 3 60 Example 4 50 Example 5 100 Example 6 40Example 7 70 Example 8 60 Example 9 40 Example 10 10 Example 11 30Example 12 30

In the above examples, the packaging bag having the aluminum foillaminated film as the light-absorbing or light-reflective film 24 showsthe superior sustainability of moisture absorption capability, and thepackaging bag having the first and second packaging materials bothcontaining the desiccant-containing resin film shows fine moistureabsorption capability. The aluminum-evaporated film and thelight-absorbing film each have a base material of a PET film, in whichcase the moisture absorptiveness of the desiccant reaches saturationfaster compared to the case of the aluminum foil laminated film.Superiority in the sustainability of moisture absorption capabilitymeans that a longer time is required for the moisture absorptiveness ofthe desiccant to reach saturation. The sustainability of moistureabsorption capability of the desiccant can be adjusted by adjusting anamount of the desiccant contained in the packaging bag.

The saturation reaching time of the moisture absorptiveness of desiccantof the desiccant-containing resin film is acceptable if the time isequal to or longer than a dry state maintenance time required for astored article. When moisture-proof capability higher than that ensuringsaturation times of the above examples is required, the highermoisture-proof capability is achieved by increasing the desiccantcontent of desiccant-containing resin of the desiccant-containing resinfilm, and increasing the thickness of the polyolefin resin film overlaidon the desiccant-containing resin or enhancing the capability of thetransparent barrier film.

In the above embodiments, each of the transparent barrier film 12, thepattern printed film 23, the desiccant-containing resin films 11 and 21,etc., is depicted as a single layer in FIGS. 2( a) to 2(d) and 4(a) to4(d). This single layer includes a film overlaid thereon by thecoextrusion process, etc. When an oxygen barrier property, a gas barrierproperty, oil resistance, etc., is required, therefore, a proper resinmay be selected and overlaid on the single layer by the coextrusionprocess.

The packaging bag of the present invention achieves a saturationreaching time of moisture absorptiveness of the desiccant of 100 days ormore.

INDUSTRIAL APPLICABILITY

The packaging bag of the present invention is a packaging bag forstoring an article need to be kept in a dry state, and is effective as apackaging material for use in storing a food, electronic component,medicine, book, etc. The drying agent with a moisture absorptionindicator function according to the present invention can be placed in acontainer that stores a food, electronic component, medicine, book,etc., to be used as a drying agent.

EXPLANATIONS OF REFERENCE NUMERALS

-   -   1 Moisture absorbent sheet    -   2 Moisture-absorbing humidity indicator    -   3 Barrier film    -   4 Bag    -   6 Hollow container    -   7 Inner container    -   7 a Synthetic zeolite    -   8 Cap    -   10 First packaging material    -   11 Desiccant-containing resin film    -   12 Transparent barrier film    -   13 Sealant film    -   20 Second packaging material    -   21 Desiccant-containing resin film    -   22 Thermoplastic resin film    -   23 pattern printed film    -   24 Light-reflective film or light-absorbing film    -   25 Transparent barrier film    -   30 Moisture absorption indicator pattern    -   40 Heat seal portion    -   45 Space    -   61 Transparent desiccant film (main desiccant layer)    -   64 Moisture permeable film    -   65 Bag-like portion    -   66 Silica gel    -   70 Indicator film layer    -   71 Moisture-absorbing film    -   73 Pattern printed layer    -   75 Barrier film    -   76 Moisture permeability control film    -   80 Moisture absorption indicator pattern    -   75 Barrier film    -   76 Moisture permeability control film    -   A Article

1. A packaging bag with a moisture absorption indicator function,characterized in that: the packaging bag comprises a first packagingmaterial and a second packaging material joined together while anarticle storage space being formed therebetween; at least the firstpackaging material out of the first and second packaging materialsincludes a transparent barrier film disposed on an outermost sidethereof, the transparent barrier film having a barrier property againstwater vapor; the second packaging material includes a light-reflectiveor light-absorbing film and a pattern printed layer disposed on a baginterior side of the light-reflective or light-absorbing film, thepattern printed layer including a moisture absorption indicator pattern;and at least one of the first and second packaging materials includes adesiccant-containing resin film that becomes transparent due to moistureabsorption, the desiccant-containing resin film being overlaid on a partor the whole of the bag interior side of said at least one of the firstand second packaging materials.
 2. The packaging bag with a moistureabsorption indicator function according to claim 1, characterized inthat the second packaging material includes a barrier film on anoutermost side thereof, the barrier film having a barrier propertyagainst water vapor.
 3. The packaging bag with a moisture absorptionindicator function according to claim 1, characterized in that thedesiccant-containing resin film comprises a laminate formed of adesiccant-containing resin layer and a thermoplastic resin layer.
 4. Thepackaging bag with a moisture absorption indicator function according toclaim 1, characterized in that: the transparent barrier film comprises abase film that is provided thereon with a silica- or alumina-evaporatedfilm, a multilayer-evaporated film of silica and alumina, a siliconnitride-evaporated film, a coating layer of a barrier paint, or a layermade by coating an evaporated film with a barrier paint; and thetransparent barrier film has a water vapor transmission rate of 0.001 to100 g/m²/day.
 5. The packaging bag with a moisture absorption indicatorfunction according to claim 1, characterized in that: thelight-reflective film is a film having a metallic luster that comprisesan aluminum laminate film, an aluminum-evaporated film, aninorganic-evaporated film, or an inorganic oxide-evaporated film; andthe light-reflective film has a water vapor transmission rate of 0.001to 100 g/m²/day.
 6. The packaging bag with a moisture absorptionindicator function according to claim 1, characterized in that: thelight-absorbing film comprises a film coated with or containing alight-absorbing material, or a film laminate having a film coated withor laminated with a light-absorbing material; and the light-absorbingfilm has a water vapor transmission rate of 0.001 to 100 g/m²/day. 7.The packaging bag with a moisture absorption indicator functionaccording to claim 1, characterized in that: the pattern printed layercomprises a polyolefin film that is provided on the desiccant-containingresin film or on the light-reflective or light-absorbing film; themoisture absorption indicator pattern is a pattern including acharacter, numeral, design or a mixture thereof appropriately combined,which is printed on at least one surface of the polyolefin film; and thedesiccant-containing resin film becomes transparent as a desiccantcontained in the desiccant-containing resin film approaches saturationin moisture absorption, to thereby allow visual recognition of themoisture absorption indicator pattern from the inside or outside of thepackaging bag.
 8. The packaging bag with a moisture absorption indicatorfunction according to claim 1, characterized in that: the patternprinted layer is provided on the desiccant-containing resin film or onthe light-reflective or light-absorbing film; the moisture absorptionindicator pattern is a pattern including a character, numeral, design ora mixture thereof appropriately combined, which is printed on at leastone surface of the desiccant-containing resin film or of thelight-reflective or light-absorbing film; and the desiccant-containingresin film becomes transparent as a desiccant contained in thedesiccant-containing resin film approaches saturation in moistureabsorption, to thereby allow visual recognition of the moistureabsorption indicator pattern from the inside or outside of the packagingbag.
 9. The packaging bag according to claim 1, characterized in thatthe desiccant-containing resin film contains at least one desiccantselected from zeolite, silica gel, and alumina.
 10. The packaging bagwith a moisture absorption indicator function according to claim 1,characterized in that the first packaging material is located on a frontside of an article stored in the packaging bag, and the second packagingmaterial is located on a back side of the article.
 11. The packaging bagwith a moisture absorption indicator function according to claim 1,characterized in that the light-absorbing film is a film printed withblack ink, or is a film made of a thermoplastic resin having carbonblack mixed therein.
 12. The packaging bag with a moisture absorptionindicator function according to claim 1, characterized in that thedesiccant-containing resin film is mixed or coated with alight-scattering material.
 13. The packaging bag with a moistureabsorption indicator function according to claim 1, characterized inthat the transparent barrier film is coated with a light-scatteringmaterial.